The last several years has seen an increasing emphasis being placed on the design of engines to make them more compact, lighter and yet with improved fuel economy, efficiency, reduced emissions, greater service life and increased power output per cylinder. As present day engines are converted or upgraded, the piston assembly is subject to even higher combustion chamber pressures and temperatures.
Attempts have been made to overcome the effects of higher combustion chamber pressures by altering the design of the piston member to include perforated gussets and increased cooling ribs. An example is disclosed in U.S. Pat. No. 4,502,422 issued to David E. Brann on Mar. 5, 1985. A piston and a carrier member are removably attached together and retained by a snap ring. A trunnion pin is positioned within a pair of struts members in the carrier member and is bolted to the connecting rod. Thus, the struts surround the pin and are in rotational relationship thereto.
Another example of a piston assembly is disclosed in U.S. Pat. 4,644,853 issued to Robert A. Russell et. al. on Feb. 24, 1987 wherein a piston assembly has a head member and a skirt member being connected with a pin which is bolted to a connecting rod. The piston head member includes a piston pin connecting section having a pair of arms encircling the pin and structurally connecting the pin to the piston head member in a generally conventional manner.
In another example, U.S. Pat. No. 4,013,057, issued to William D. Guenther on Mar. 22, 1977, discloses a piston assembly. The piston assembly includes separate head and skirt portions. The head portion includes a generally tubular-shaped bearing member having a wrist pin positioned therein and the wrist pin being bolted to the connecting rod. The bearing member, although having an opening therein, extends cylindrically around the pin a sufficient distance to insure that the head portion and the pin remain connected during operation of the piston assembly.
Each of the above described patents discloses a high performance piston assembly. In the structures described, the components are heavy, include excessive structural material and increase the complexity of the engine design by contributing to increased inertia, stresses and weight. For example, each of the pistons include a pair of struts or connecting members which surround or at least partially surround the wrist pin.
The present invention is directed to overcome one or more of the problems as set forth above.